Physics-171- 18 and 19

Atoms are the smallest building blocks of elements. When different types of atoms are combined (by chemical reaction), they form

Molecules, Molecule, or Chemical compound

Except for the lightest elements, the ____ number is generally larger than the atomic number

Neutron

What is uranium enrichment?

Uranium enrichment means increasing the content of uranium-235 in natural uranium samples Uranium enrichment means decreasing the content of uranium-238 in a natural uranium samples.

Match the statements on the right side with the suitable entry on the left

Uranium-235 - is a naturally scarce, fissionable uranium isotope. Its nuclei split when bombarded by neutrons, releasing enormous energy and extra neutrons. Uranium-238 - is the most naturally abundant uranium isotope. It absorbs neutrons and is less likely to undergo fission reaction.

Which of the following is true about uranium isotopes?

Uranium-235 is likely to split when bombarded by slow neutrons. Uranium-238 is more abundant in nature.

In a fusion reactors, the chain reaction requires

Very high temperatures

Most reactors use water as a moderator instead of graphite because

Water can also be used as a coolant

If a nuclei consist only of a protons, this would necessarily mean that the magnitude of the charge of the nucleus

Would be an integer multiple of the charge of a single proton. Would be large than expected

Which types of particles or radiation are generated by a cathode-ray tube?

X-rays Electrons

The ____ number determines how many electrons are outside of a neutral atom, which in turn determines the chemical properties of the atom.

atomic

Why enormous energy is released from a hydrogen bomb?

because the combined mass of the reaction products is less than the combined mass of the initial reactants. Because of Einstein's famous equation E=mc2 Because of the nuclear fusion.

When an electron jumps from one orbit to a lower energy orbit, light is ____ by the atom

emitted, radiated, or ejected

Which of the following are possible values for the angular momentum of an electron in Bohr's new model of the atom?

h/2pie 5h/pie

The fission reaction was discovered when bombarding uranium with neutrons yielded products with ___ atomic numbers

smaller or lower

By knowing the velocity and the extent of deflection produced by the magnetic field, Thomson could estimate the _________ of the particles.

Mass

In a fusion reaction, deuterium(H2) and tritium(H3) nuclei fuse to form an alpha particle plus a neutron. Consequently, an amount of energy will be released according to

Mass to energy conversion E=MC2

The role of a ___ in the nuclear reactor is to slow down neutrons so that they are more likely to be absorbed by uranium-235.

Moderator

Water is used both as a ___ and a ___ in nuclear reactors.

Moderator Coolant

The energy of the stable orbits in hydrogen is given by the formula E= E0/n2 , where E0=-13.6 eV. The energy level of the second excited state (n=3) is ____ eV.

-1.5, --1.5, or -1.51

The energy of the stable orbits in hydrogen is given by the formula E= E0/n2 , where E0=-13.6 eV. The energy level of the ground state, the lowest state possible, is ____ eV.

-13.6

The energy of the stable orbits in hydrogen is given by the formula E = E0/n2, where E0=--13.6 eV. The energy level of the first excited state (n=2) is _____ eV.

-3.4 or -3.42

Rank the following (from smallest to largest) based on their masses.

1. Hydrogen atom 2. Alpha particle 3. Nitrogen atom

Rank the following according to most massive first and least massive last

1. Hydrogen atom 2. Proton 3. Electron

Rank the following based on their penetrating power (from highest to lowest)

1. Neutrons 2. Gamma radiation 3. Alpha particles

Rank the following nuclei based on the excess neutrons they are likely to produce when they split

1. Nucleus Y with proton to neutron ratio of 0.6 2. Nucleus X with proton to neutron ratio 0.8 3. Nucleus Z with proton to neutron ratio of 1

In an enriched uranium sample, the proportion of the isotope uranium-___ is increased above its natural proportion.

235

When the isotope uranium-___ absorbs a neutron, it ultimately produces another fissionable element known as plutonium

238

Natural uranium has a very high content of the isotope uranium- ___ and very low content of the isotope uranium-___

238 235

The isotope 23V51 has ____ neutrons in its nucleus.

28

A newly formed element X starts to decay to element Y with half-life of 5 million years. In 10 million years, the ratio between Y and X is

3:1 Reason: Ten million years represents two half-lives. Therefore, only 25% of the element X remains, the remaining 75% has decayed into element Y. Thus, the ratio of Y/X is 75:25 which equals 3:1

Identify the match from the left side that replaces the question mark in the right side

4 2 He - 6 3 Li + 2 1 H > 4 2 He +? 17 8 O - 5 3 He + 14 7 N > ? + 1 1 H 3 1 0 n - 235 92 U + 1 0 n > 144 65 Ba + 89 38 Kr + ?

At a given frequency of light, f , which energies are allowed? The variable h is Planck's constant.

5hf 42hf

Match the numbers (in the left column) with the names these numbers represent (in the right column) for the isotope 7N15

7 - Atomic number N - Chemical symbol 15 - Mass number

If the nucleus of atom Y is 18 times heavier than that of hydrogen and element Y has an atomic number of 8, then the number of protons is ___ and the number of neutrons is ___

8 10

When the element 88X226 emits an alpha particle, the resultant element will be ___

86Y222

An electron has a mass of ____ x 10-31 KG and a charge of ____ x 10-19 C.

9.1 -1.6

Which of the following statements are true.

A blackbody's spectrum depends on its temperature. A blackbody's spectrum is continuous.

Which of the following statements are true for a cathode ray tube?

A dark region starts to form near the cathode and then moves across the tube toward the anode as the pressure is further reduced. As air is pumped out of the tube, a colorful glow first appears in the gas near the cathode.

Match the following spectra with its source

A discrete spectrum - An element A continuous spectrum - A blackbody

How can fission reaction be initiated?

A fission reaction can be initiated by high-energy protons. A fission reaction can be initiated by high-energy neutrons. A fission reaction can be initiated by high-energy alpha particles. A fission reaction can be initiated by low-energy neutrons.

Isotopes are detected by passing nuclei of known velocity through a magnetic field and observing how much their paths are bent under the influence of

A magnetic force

Gamma decay results in

A more stable version of the same element

Select the characteristics of a proton

A proton is much more massive than a electron A proton has a positive charge which is the same in magnitude as an electron's

The role of control rods in the nuclear reactor is to ___ neutrons to control the rate of the reaction

Absorb

The conservation of linear momentum in alpha decay requires that

After the decay, the alpha particle and the daughter nucleus emerge in opposite direction. After the decay, the alpha particle is always faster than the daughter nucleus

An element 88X226 is radioactive and decays into 86Y222. The radioactive process that has occurred is called ____ decay

Alpha

Elements in the same family (column) on the periodic table have the same or similar

Atomic proportions with other elements. Chemical properties.

In the periodic table illustrated by Mendeleev, the elements are arranged in the increasing order of their

Atomic weight

Why a chain reaction does not occur for a uranium ore?

Because of the low content of the fissionable uranium-235. Uranium-235 is more likely to absorb the extra neutrons.

Why is energy released in a nuclear reaction?

Because the mass of the parent nucleus and the bombarding particle is more than the combined mass of the reaction products. Because of Einstein's famous equation E=MC2

What are the similarities between a plutonium bomb and a uranium bomb?

Both plutonium and uranium bombs require chain reactions Both plutonium and uranium bombs employ nuclear fission Both plutonium and uranium bombs produce enormous amount of energy Both plutonium and uranium bombs reaction starts with a subcritical mass of fuel

How does a fission reactor produces energy to drive electric turbines?

By splitting heavy nuclei into smaller ones thus releasing energy By making use of Einstein's famous equation E=MC2

What was the question that de Broglie asked that lead to the development of quantum mechanics?

Can particles behave like waves?

The rapid growth of the number of subsequent fission reactions due to excess neutrons produced in each fission is called a ___ reaction

Chain

Planck's formula forced him to face a radical conclusion

Light could only be emitted in discrete chunks. Light could only be absorbed in discrete chunks.

Which of the following equations best explain the energy released in a fusion reaction?

E=mc2

A positron is a positively charged

Electron

According to Bohr's model, the centripetal acceleration for an electron orbiting about nucleus is given by the ___

Electrostatic force

Which of the following are discrete?

Element's spectrum Energy

Identify the true statements about elements after the systematic study

Elements ground up together could always be separated out to retrieve the original elements. Elements mixed together could be heated to form a new substance

The linear momentum of the parent nucleus before an alpha decay should

Equal the combined linear momentum of the decay products

True or False: In a chemical reaction, the atoms of elements combine in different ways and the fundamental nature of the atoms change

False

Match the statements on the left with the suitable entries on the right

Fast neutrons are more likely to be absorbed by - Plutonium-239 Slow neutrons are more likely to be absorbed by - Uranium-235

Nuclear ___ is the process whereby one massive nucleus splits into smaller nuclei.

Fission

A nuclear reaction that combines small nuclei to form larger ones is called a ___ reaction.

Fusion

A nuclear reaction that combines small nuclei to form larger ones is called a ___ reaction. (Use one word in the blank.)

Fusion

Match the particles and rays on the left column with their characteristic on the right column

Gamma radiation - has no charge or mass Beta particle - has the mass of a single electron Alpha particle - has two protons and two neutrons

Which of the following factors influence the glow of cathode ray?

Gas pressure Type of Gas

To produce an atomic spectrum pattern, an element must

Have its emitted light separated through a prism. Be heated to high temperatures.

Match the following pairs

If the nucleus is made only of protons - the nuclear charge would be larger than the known value If the nucleus is made only of neutrons - the nuclear charge would be zero If the nucleus is made of neutrons and protons - the nuclear charge could be explained

Which of the following statements are true for a fission chain reaction?

In a fission chain reaction, extra neutrons are produced in each step. In a fission chain reaction, enormous energy is produced. In a fission chain reaction, a rapid growth of subsequent fission reactions takes place

What happens during a nuclear fusion reaction?

In nuclear fusion, energy is produced In nuclear fusion, small nuclei fuse to form a larger nucleus

The de Broglie hypothesis was that the momentum of the particle was _____ proportional to the wavelength of the particle.

Inversely

Which of the following statements are true of natural radioactivity?

It does not require any special preparation process. It is produced continuously by compounds containing uranium or thorium. It does not require any apparent source of energy to produce radiation.

If the half-life of a radioactive isotope X is 10 days, which of the following statements are correct?

It takes 10days for half of the amount of X to decay. In 20 days, there will be one-fourth of the original amount of X left.

What are the policies proposed by the government on fission reactors' waste disposal?

Leaving the remaining uranium in the waste without separating it. Burying the waste in solid rock formations.

Energy is released from a nuclear fission reaction because the combined mass of the products is ____ than the combined mass of the parent nucleus and the bombarding neutron

Less

The advantage of using heavy water instead to light (ordinary) water in nuclear reactors is that heavy water is ___ likely to absorb neutrons.

Less

Which of the following statements are true about plutonium?

Plutonium is fissionable by neutrons Plutonium is a by-product of a fission reactor Plutonium is a decay product of uranium

The charge of a proton is equal in magnitude to a electron's but is

Positive

Match the atomic components (in the left column) with the appropriate numbers of these components (in the right column) for the isotope 29Cu65

Proton - 29 Neutron - 36 Neuclons - 65

When nitrogen nuclei are bombarded by alpha particles, ___ are emitted. This reaction is called a ___ reaction

Protons Nuclear or fusion

Planck discovered that the energy from the blackbody could only be emitted in ____ of energy

Quanta Discrete chunks

In fission reactors, most of the nuclear waste is

Radioactive

___ neutrons are more likely to be absorbed by uranium-235 and initiate a fission reaction, while ___ neutrons are more likely to be absorbed by uranium-238

Slow Fast, Energetic, Speedy, or Quick

What are the reasons for slowing neutrons down to achieve chain reactions?

Slow neutrons are less likely to be absorbed by uraium-238 Slow neutrons are lore likely to be absorbed by uranium-235

Nuclear fission releases extra neutrons because

Smaller nuclei have a lower neutron to proton ratio compared with bigger nuclei. The parent nucleus contains significantly more neutrons than protons.

Which of the following use nuclear fusion reaction as a the energy source?

The Sun Thermonuclear bombs

Which of the following statements are true about the atomic number of an element?

The atomic number of an element is the number of electrons needed outside the nucleus to make the atom neutral. The atomic number of an element determines its chemical properties. The atomic number of an element is the number of protons in the nucleus of the atom

In a fission reaction, subcritical state means that

The chain reaction cannot be sustained. The mass of the initial fissionable fuel is less than the critical mass.

In a nuclear reaction

The charge and mass numbers add up to the same total before and after reaction. At least one nucleus will transform to another

In Bohr's new model of the atom, he had to assume something that was different from what classical physics predicts. Which of the following statements is the correct assumption?

The electrons had stable orbits in which they did not radiate energy

Producing commercial power from fusion has not been achieved mainly because of

The enormous temperature required for its operation

In a fission reaction, supercritical state means that

The mass of the initial fissionable fuel is more than the critical mass

In nuclear fission, a chain reaction occurs if

The nuclear reaction is initiated by one neutron and the fission produces an excess of neutrons.

A proton is

The nucleus of a hydrogen atom

Match each entry on the left with its corresponding statement on the right

The nucleus of the hydrogen atom - consists of a single proton. The nucleus of the atom of the most elements - consists of protons and neutrons. The nucleus of the helium atom - consists of two protons and two neutrons. The atom of every element expect hydrogen - consists of protons, neutrons, and electrons.

When a neutron is absorbed by the uranium-235 nucleus,

The uranium nucleus splits into smaller nuclei and more neutrons are emitted. A nuclear reaction occurs.

Which things are true about particles and their anti-particles?

They have the opposite-sign charges They have equal masses

The spectrum of electromagnetic waves produced by any element is ____ to that element

Unique, Specific, or Characteristic